U-shaped vibrator armature and damped arm mechanism



C. HUETTEN Aug. 5, 1952 U-SHAPED VIBRATOR ARMATURE AND DAMPED ARM MECHANISM Filed June 17, 1949 INVENTOR. fllarence Fad/en Patented Aug. 5, 1952 U- SHAPED VIBRATOR AElldjA'IU'R-E DAMPED ARM MECHANISM" Clarence Huetten, Indianapolis, Ind:, .assignonto P. R; Mallory & .00., Inc., Indianapolis-Ind a,

corporationof Delaware Application June 17, 1949; sari-amass}? 32 9 Claims (Cl. 200-90 This invention: relates generally'tdelectrical v which acts to decrease the, efiiciency of thevibra-i tor. Further, because of the unrestrained impact, the abutting contact members, become eroded quickly so that after ,a relativelyshort time these contacts must be replaced. It is apparentthat. I as the frequency of the vibrator increases these conditions become more pronounced; andv create a. definite operating problem.v

At lowand medium vibrator frequencies atv tempts have been made-to meet this: problem by providing,; stopped arm vibratorimechanisms in condition: known; as vibrator-chatter occurs which a stop is providedlfor abruptly restraining;

the; amount of swing of a: compliant contactmemben It has-been 'found,however-, .thatsatu high vibrator frequencies, for examplc of the order of approximately 250 cycles per second; this expedient does not work satisfactorily since therev is an abrupt. forcefulstop insteadv of the graduated cushioned effect desired.

Further, another problem has beenrfound-in the construction of, high-frequency vibrators be-.-.

cause of the. fact that the power requirementsfor high. frequency vibrators are different than that 1 Design expedientsx used for these low frequency vibrators have beenfor 'low frequency vibrators.

foundotorbe unsuited .for high frequency operation. This is so becauseyibrator. armatures used in..,low frequency devices are often constructed so that, if used at highfre'qu'ency operation, maxi mum'power is notobtainable. Particularly is this truesince' at high'frequencies the armature am plitude'may be relatively small. Thus; since the power developed by' the armature-dependsto-a large extenton the increase ofmagneticfiuxbetween the pole pieceand the armature as-it' niove's toward: the pole it is apparent thatif Y the arma ture construction does'not provide for maximum permanenceichange, the: vibrator mustcbe 'underr;

powered;

In the present high frequency vibrator invene:

2; tion;theseatwolproblems; above; have been: faced-,2.- and:the:'difiicultiesiresultingitherefroinshavezbeenrz: substantially overcome, with meanscb'einga prd-a videdfornvercoming the losses-:in vibraton operation. due to-itheiuseizofai(a); improper (damping;

and lb) improper constnuctiontofithe. reed. arniaa tureh,

To overcome the first problemraadampediarmn mechanism V.:ha-si;been rprovi'ded, lWhereiha-ascoiripliant;contactrbearingrmemberiiszbiase v a second compliant.- menrben withqa xfo'llom or travelxrelationship;thereto;lequahat "least .tocthee defletiont of;ihescbntaci: arm; Theitwo-z'arms z moreoven: are:cocperativelymaintained together: so that they doinoti separateiin .opera'tionytnando have been so 'consitructedethat: thereeisz aadefin'itez-frictional motionaestazblishe'd therebetweeni Thus-,:-intthe;.prese'nt novel dafnped' arm construc's tion, a damper spring mechanismr'is:placedzibeai hind the contact bearing spring adja'centdtstassociated fixed .con'ta'ct'st; so cthat thezadjustable relation between the damperispringsand itsi-cone: tact: bearing ii member; produces a: correlative"; change zinficontact':spacingsbetweenstlie bearings; contact and the fixed contactv'tdacompensate for thenchange in: spacing 'between theses-contactsTdue tozi 'erosion;

Secondly; inorder tdrprovideroptimum powem change betvve'en' the; armature and -its'vassociated a arm" piece; a :novel armature. isvconstructed: so East:-

to obtain maximum permanence changevthereinie After: rgreati effort andr experimentation-At was found :tha'trthexwidth -:'of the *armatureds critical: inztheahighrfrequency:construction thereof; and thaninther armature width iwere madewsubstanstially eq lalw tethe width? of: itsilpclepiece, thencgreater permanence/2 change is obtained in :thearmature asiit approaches its 'pole-t-.pi'eoe.:=. Furthen; it: was also 1 found that? the "length o--?the armature -isi. of :a criticabdimension thatr a; i'd efi-Q'E niteiarmature i length proportionally: relatedl-toi-tthe-\awidth of itsassociatedpole-"piece: provides a dimensionalx construction? such that: theeperma-x nence changetin-the armaturecoulabeadditively; affected andimproved as it approachedtheapolea zpiece giving a maximum power efficiency a By utilizing thesecfind-ings; v:2the-i:present":tin vention: includes rv an-.t.armature and .pole-;-pi,ece

whereby; the: above :criteria are constructional-1y 5' achieved 'so as toiobtaim maximum 1" permanence :change in the armature for giving maximum-1* vibratorpower, This -rarmature hase beenaconstructcd having a portion offset from: UitSxCOIX-i'a nected reed-structurewith n-a :second portiombent' in a plane substantiai-lyqdifierent front -the- :1" oL-ther connected-:reed structiir'ezev Further-r the armature is built to have the same width as its adjacent pole piece;

Thus, this greatly improved high frequency armature cooperating with the novel damped arm mechanism, priorly stated, provides a high frequency vibrator operating with minimum frictional contact losses and at maximum power level.

It is, therefore, an object of the present invention to provide a vibrator using a novel high permanence change type of armature and damped contact arm mechanism having low frictional loss characteristics whereby high frequency operation of the order of hundreds of cycles per second is achieved at a maximum efi'iciency.

Still another object of the present invention is to provide a high frequency interrupter mechanism having a damped arm contact mechanism and an armature having the characteristic of high permanence change upon its approach to the pole of said interrupter and whereby maximum magnetic flux linkage is thereby provided in said armature.

Still another object of the present invention is to provide a high frequency vibrator assembly having an operating frequency of the order of N 10 cycles per second where N may be an integer greater than 1.. q

Yet another object of the present invention is to provide in a high frequency vibrator operating above 200 cycles per second. a damped arm mechanism having a plurality of. springs, one of which rests upon the other so as to dampen its oscillations so that said high frequency vibrator is operative with a minimum of noise.

Another object of the invention is to provide a high frequency vibrator operating at a frequency of the order of hundredsof cycles per second at maximum power and life. v

Another object of the present invention is to provide an armature in a high frequency vibrator having the same width as its pole piece and having an extent constructed to give a high permanence change in said armature upon its approach to said pole piece;

Still another object of the present invention provides in a high frequency vibrator a novel armature mechanism having a U-shaped form and providing optimum flux linkage between said armature and its pole piece upon the approach of said armature thereto.

The invention, in another of its aspects, relates tonovel features of the instrumentalities described herein for teaching the principal object of the invention and'to the novel principles employed in the instrumentalities whether or not these features and principles may be used in the said object and/or in the said field.

Other objects of the invention'and the nature thereof will become apparent from the following description considered in connection with the accompanying figures of the drawing and wherein like reference characters describe elements of similar function therein and wherein the scope of the invention is determined rather from the dependent claims.

'Referring now to the figures of the drawing:

Figure 1 is a front elevational view-of an embodiment of the invention useful in showing the constructional arrangement of the separate units thereof;

Figure 2 is a side elevational view of the vibrator invention shown in Figure 1 adapted to show the novel high frequency armature with its associated damped spring mechanism;

Figure 3 is a side elevational view of the frame structure used in the embodiment of the invention;

Figure 4 is a profile view of the armature and damped arm mechanism shown in the embodiment of the invention shown in Figure 1; and

Figure 5 is an elevational embodiment of the invention showing the use of a pair of felt protector caps enclosing end portions thereof.

Generally speaking, the present invention comprises a current inverter operating at high frequencies of the order of 200 cycles per second. The vibrator includes a high frequency armature connected to a vibrator reed. The armature is multi-sectioned with one of its sections offset from the axis of the adjoined reed, and has a second section bent in a plane substantially differing from the plane of the offset section. The armature is further dimensionally constructed with an extent and width having a direct correlation to the width of its associated pole piece. By means of this construction the high frequency armature is adapted to develop maximum permanence change as it travels towards its pole piece and thus to develop maximum power characteristics.

-bias springs slideably and frictionally engaging the undersides thereof to increase the high frequency contact eificiency thereof. Thus, each pair of spring members, i. e., the contact member and'its bias spring, is cooperatively maintained together so that they do not separate in action when making'contact with associated substantially fixed side contacts. In this manner a combined damping and compensating function is achieved by the bias spring so as to adjustably "allow for proper contact make between fixed and compliant contacts while compensating for the erosion of the contact points of the vibrator.

Referring now to the drawing, there is shown in an embodiment of the present invention a high frequency vibrator generally designated by reference numeral 8 for operating at frequencies of the order of 200 cycles per second. Vibrator? has a hook shaped ferro-magnetic frame having a pair of apertures E22, E23 (Fig. 3) denoted by reference character 18 and has a narrowed hook portion I I around which there-is provided a wire wound driver coil I2 adapted to be current excited from a suitable supply source.

A stack generally denoted by reference character 53 is secured to the lower extremity of ferromagnetic frame Hl asby means of a single stack screwit and nut 15. The stack comprises a plurality of spacers i6, Eta, [5b, I60 which may be fabricated of an electrically resistive material. Between spacers l6 and Mia and Nib and IE0 there are included side contact arms I8 and I9 substantially fixedly maintained therebetween as by means of the tight locking afforded by means of stack screw it and nut l5. Clampedibetween spacers 16a and Nib, at its lower extremity, is a hinge member '28 to which is joined a main reed.

2i and an armature 36 which maybe integrally formed and connected thereto atits upperend. All of the spacers of the stack are providedwith The structure of the vibratory system will be generally understood from Figures 2, 3 and 4. It will be noted that this system is built around reed 9 having a main body section 2|, a narrow neck portion 26 integrally formed therewith and shoulders 29 and 3| connecting the said two portions. The entire reed structure 9 is maintained within stack I2 as by the use of resilient hinge member 20 which may be constructed and fabricated of a tempered steel. Resilient hinge 20 has a top section'33, a step section 34 and a narrowly constructed auxiliary reed member 35 integrally formed therewith so as to have a main body portion 36. Hinge 29, it is to be noted, has for purposes of alignment, a hole 39 cut therethrough andalso cut-out U-shaped apertures 49 and 46.

At an end 31 of the auxiliary reed 35 there is mounted a vibrator driver contact 38 which is so constructed that it fits between neck section 26 and shoulder 3I of main reed '29 and has main body 36 of auxiliary reed 35 placed in a fiat manner adjacent main body section 2| of reed 9. Vibrator driver contact 38 is adapted to cooperate with a normally closed stationary contact 64 mounted at the end 55 of driver contact assembly 42. Assembly 42 comprises end section II, extension I42 horizontally extending therefrom, a section 43 integrally formed with and vertically extending from extension 42 and a connected top .bent "section 44 lying adjacent upper portion 58 of frame Ill. 'Bent portion section 44 is mounted against frame I9 as by means of an unitarily formed abutment 5I spot welded to frame II] at points 60 and BI. In this manner driver contact 64 is maintained in a yielding yet substantially fixed manner for intimate contact with vibrator driver contact 38.

A second stack I0 is provided so as to clamp in a substantially fixed arrangement compliant vibrator arms 'II and I2, reed 29 interposed therebetween, a portion of hinge 29, and spring biasing members 89 and 8| for frictionally engaging arm H and I2. The entire assembly is stack constructed by providing metal plates 82 and 83 at each end of second stack III for riveting the entire assembly as by means of rivets 85 and 86. Vibrator contact arms 'II and I2 and contact points 50 and 9| placed at the tip ends thereof are adapted on the operation of reed 29 to make contact with associate side contacts 24 and '25. In order to afford frictional bias for vibrator contact arms 'II and I2 which, as stated, are of resilient construction and in order to provide a predetermined amount of cushioning restraint for contact make .and break between these members and side contacts 24 and 2I, bias spring members 89 and SI provide individually truncated sections, such as 92,, backing up the said compliant arms II and I2 in a frictionally slideable manner at a point'on vibrator arms II and I2 beneath contacts 99 and .JI thereof. It is to be noted that in mounting biasing or backing members 89 and 8I in stack I0 there are provided spacers I0! and I98 between vibrator arms II and '72 and biasing members 89 and GI in order to increase the frictional effects therebetween with the deflection of the members.

Connected to neck 26 of reed arm 29 is a generally 'U-shaped armature 39 which may be integrally formed therewith. Armature 30 comprises an armature section I00 offset from the reed substantially in a longitudinal plane thereto, a bent portion I03 vertically extending from said offset section and a third section I I3 connected to said second section but extending substantially in a plane at right angles thereto.

'As stated, hook II depends from frame III and penetrates 0611 I2 substantially in the center thereof. Further, coil I2 may have a pair' of fiber washers H4, H5 fitted thereagainst in a substantially horizontal plane. At the end of dependent hook II is a magnetic pole piece I05. When coil I2 is energized, or current excited, pole piece I05 is adapted to magnetically attract armature I00 at a predetermined frequency. It is to be noted that hook II and pole piece I have substantially identical end'widths less than the width of associated ferro-magnetic frame I0 and as constructionally shown at point I96 thereof.

Since greater mechanical power is required for vibrators operating at a frequency of the order of 200 cycles per second it was found necessary to construct an armature built so as to supply the necessary additional power. Lower frequency armatures, it was found, could not provide the desired power increase. Since the power requirements depend to a great extent upon the permanence change in the armature it was found that an armature was needed which would give increased permanence change with deflection toward the pole piece.

After considerable experimentation it was found that the increased permanence change could be obtained primarily in two ways. It was discovered that the armature end had a direct correlation to the width of its associated pole piece and that for optimum construction of such an armature the width thereof had to be substantially equal to that of the associated pole. In this respect it was found that when the armature end was wider than the pole piece, added permanence was obtained but the permanence change was reduced. Armature ends less than the width of the pole piece reduced the permanence change.

It was further found that the length of the armature was necessarily critical in attempting to obtain maximum permanence change with deflection of the armature toward the pole. This length was found to be greater than the armature thickness. Thus for the necessary permanence change fulfilling the power requirements at high frequency operation of the vibrator it was necessary to provide added length to the armature. This was done by forming the armature end in (a) a generally U-shaped configuration having portions oifset to vertical axis of the reed and (b) having a width substantially the same as its adjacent associated pole piece.

In the operation of the present vibrator the circuit organization is substantially generally known to those skilled in the art, and hence does not require any detailed description here. It is sufficient to state that the several contacts are so adjusted that in normal rest position the driver contacts are closed and the other contacts are open. The relatively fixed interrupter side contacts are connected to two ends of the primary'windings of a center tapped step-up transformer with the pulsating output taken off the secondary winding of said transformer. A source of low voltage current is connected to the center tap of the primary winding and the main reed. The driver circuit comprises the driver contact connected in series wtih the driver coil and the source of current.

Upon closing the circuit of the vibrator, the driver circuit will be energized and driver coil I2 will attract armature 39 as by deflecting main reed 9 so as 'to break the driver circuit. However, the inertia ofthe vibratorysystem iwill cause continuation of the displacement of the armature of main reed- 9 in the same-direction until resilient or compliant arm 12 makes contact with its associated side contact member 24. The force form deflected reed arm 12 will now return the vibratory structure in the opposite direction past the center portion thereof until resilient vibrator arm '.'I makes contact with its associated side contact It. The driver circuit will then again be closed between driver contacts 33 and 64 and will again deflect the main and the auxiliary reeds by means of the energized driver coil.

Since, however, the vibrator reed is operating at high frequencies it is necessary, in order to maintain maximum efficiency for the vibrator, that contact make between the separate contact elements be adjusted soas to substantially prevent abrupt contact therebetween in an essentially cushioned manner. Further, since the greater frequency may accentuate the erosion tendencies between the separate contacts it is necessary to provide means for compensation in the spacing between the contacts due to such erosion.

To effectuate the above cushioning between contacts and to compensate for their erosion tendencies the present vibrator mechanism provides a damped arm biasing construction whereby the contact made between the vibrator contact member and its associated fixed side contact is adjusted to provide cushioned contact engagement. Backing spring members 39, Si are adapted to underlie resilient arms 1| and i2, and to frictionally engage said arms by means of truncated sections 82 thereof. These damper springs 88, 8| bias the vibrator contactors 'H and T2 in such a way that proper relative motion occurs therebetween at maximum deflection. In addition, the damper spring tends to compensate for the spacing changes due to contact erosion. In this manner a damper arm mechanism is provided for biasing vibrator arms of the vibrator so as to prevent abrupt contact make between each vibrator contact and its associated side contact and to compensate for the erosion effects therebetween. Further, in order to substantially completely insure quiet operation for the vibrator, a pair of felt or absorbing caps I20, 12! surround the ends thereof as shown in Figure 5.

The novel high frequency mechanism including a high frequency armature and clamped arm mechanism as described above is intended to be merely illustrative and not exhaustive and since many changes could be made herein without departing from the scope of the invention, it is intended that these changes be included here.

What is claimed is:

1. A vibrator comprising in combination, a vibratory reed having a free end, means for supporting the other end of said reed, a driver coil, a frame for holding said coil having one end connected to and supported by said reed supporting meana said frame further being bent to have a hook-like configuration including a dependent portion, said dependent portion penetrating said coil substantially at the center thereof, said portion having its end constructed as a magnetic pole piece, said pole piece and dependent portion both having equal end widths less than the width of the frame from which said latter depends, said support means for said reed and said frame being positioned substantially below said pole piece, a U-shaped armature connected to said reed and cooperating with said pole piece to activate said reed upon excitation of said coil, vibrator contact arms separate from said Vibratory reed included by second support means held on said reed and adapted to move therewith, each of said arms having a frictional backing continuously slideably engaged therewith, and relatively fixed side contact arms held in said first reed supporting means and adapted to make contact with said reed contacts upon the operation of said reed.

2. A vibrator comprising in combination, a vibratory reed having a free end, means for supporting the other end of said reed, a driver coil, a frame for holding said coil having an end connected to and supported by said reed end supporting means, said frame further bent to have a hook-like configuration including a dependent portion, said dependent portion penetrating said coil substantially at the center thereof and having its end constructed as a magnetic pole piece, said pole piece and dependent portion both having end widths less than the width of the frame from which said latter depends, said support means for said reed and said frame being positioned substantially below said pole piece, a U-shaped armature connected to said reed and cooperating with said pole piece to activate said reed upon excitation of said coil, said reed and said pole piece being axially aligned, vibrator contact arms separate from said vibratory reed included by second support means held on said reed and adapted to move therewith, each of said arms having a frictional backing continuously slideably engaged therewith, and relatively fixed side contact armsheld in said first reed supporting means and adapted to make contact with said reed contacts upon the operation of said reed.

3. A vibrator comprising in combination, a vibratory reed having a free end, means for supporting the other end of said reed, a driver coil, a frame having an end connected to and supported by said reed end support means for holding said coil placed adjacent said other end of said reed, said frame further having its other end bent to have a hook-like configuration including a dependent portion extending therefrom, said dependent portion penetrating said coil substantially at the center thereof and having its end constructed as a magnetic pole piece, said pole piece and dependent portion both having end widths less than the width of the frame from which said latter depends, said support means for said reed and said frame being positioned substantially below and opposite said pole piece, a U-shaped armature connected to said reed and cooperating with said pole piece to activate said reed upon excitation of said coil, vibrator contact arms separate from said vibratory reed included by second support means held'on said reed and adapted to move therewith, each of said arms having a frictional backing continuously slideably engaged therewith, and relatively fixed side contact arms held in said first reed supporting means and adapted to make contact with said reed contacts upon the operation of said reed.

4. A vibrator comprising in combination a vibratory reed having a free end, means for supporting the other end of said reed, a coil-supporting frame having an end connected to and supported by said reed support means adjacent said supported end of said reed, said frame further having its other end bent to have a hook-like configuration including a dependent portion extending therefrom, said dependent portion penetrating said coil substantially at the center thereof and having its end constructed as a magnetic pole piece, said pole piece and dependent portion both having an end with less than the width of the frame from which said latter depends, said support means for said reed and said frame being positioned substantially below said pole piece, a U-shaped armature of a predetermined length and; having a width equal to that of said pole piece and less than that of said reed connected to said reed and cooperating with said polepiece to activate said reed upon excitation of said coil, vibrator contact arms separate from said vibratory reed and included by second support means held on said reed and adapted to move therewith, each of said arms having a frictional backing continuously slideably engaged therewith at a point, therealong, and relatively fixed side contact arms held in said support means and adapted to make contact with said reed contacts upon the operation of said reed.

5. A vibrator comprising in combination, a vibratory reed having a free end, means for supporting the other end of said reed, a coil-supporting frame having an end connected to and supported by said means adjacent the supported end of said reed, said frame further having its other end bent to have a hook-like configuration including a dependent portion extending therefrom, said dependent portion penetrating said coil substantially at the center thereof and having its end constructed as a magnetic pole piece, said pole piece and dependent portion both having an end width less than the width of the frame from which the latter depends, said support means for said reed and said frame bein positioned substantially below said pole piece, a U-shaped armature connected to said reed and cooperating with said pole piece to activate said reed upon excitation of said coil, said armature having a determined length and a width equal to that of its associated pole piece whereby maximum permanence change is obtained with deflection of the armature toward the pole, vibrator contact arms separated from said vibratory reed and included by said support means for said reed and adapted to move therewith, each of said arms having a frictional backing continuously 4 slideably engaged therewith, and relatively fixed side contact arms held in said support means and adapted to make contact with said reed contacts upon the operation of said reed.

6. A vibrator comprising in combination, a vibratory reed having a free end, means for supporting another end of aid reed, a driver coil, a frame having an end connected to said reed end supporting means for holding said coil, said frame further bent to have a hook-like configuration includin a dependent portion, said dependent portion penertating said coil substantially at the center thereof and having its end constructed as a magnetic pole piece, said pole piece and dependent portion both having end widths less than the width of the frame from which said latter depends, said support means for said reed and said frame being positioned substantially below said pole piece, a U-shaped armature connected to said reed and cooperating with said pole piece to activate said reed upon excitation of said coil, angulated vibrator contact arms having contacts at the tips thereof separate from said vibratory reed included by second support means held on said reed and adapted to move therewith, each of said arms having an angulated frictional backing whose tip underlies said contacts and makes engagement with its associated arm only at a point below said contact thus to be continuously slideably engaged therewith while the bottoms of. said backing and arms are substantially separated from each other, and relatively fixed sidecontact arms held in said first reedsupporting means and adapted to make contact with said reed contacts upon the operation of said reed.

7. A vibrator comprising in combination, a vi,- bratory reed having a free end, means for supporting another end of said reed, a driver coil, a frame having an end connected to said reed end sup-porting means for holding said coil, said frame further bent to have a hook-like.- configuration including adependent portion, said dependent portion penetrating said coilsubstarL-L tially at the center thereof and having its end constructed as, a magnetic pole piece,.said .pole piece anddependent portion both having end widths less than the width of the frame from which said latter depends, said support means for said reed and said frame being positioned substantially below said pole piece, a U-shaped armature connected to said reed and cooperating with said pole piece to activate said reed upon excitation of said coil, said armature having a portion horizontally offset to said reed, a second portion substantially perpendicular to said offset portion and an end portion bent back toward said pole piece in a plane perpendicular thereto, vibrator contact arms separate from said vibratory reed included by second support means held on said reed and adapted to move therewith, each of said arms having a frictional backing continuousl slideably engaged therewith, and relatively fixed side contact arms held in said first reed supporting means and adapted to make contact with said reed contacts upon the operation of said reed.

8. A vibrator comprising in combination, a vibratory reed having a free end, means for supporting another end of said reed, a driver coil, a frame having an end connected to said reed end supporting means for holding said coil, said frame further bent to have a hook-like configuration including a dependent portion, said dependent portion penetrating said coil substantially at the center thereof and having its end constructed as a magnetic pole piece, said pole piece and dependent portion both having end widths less than the width of the frame from which said latter depends, said support means for said reed and said frame being positioned substantially below said pole piece, a U-shaped armature forming an integral connection with said reed by means of a neck portion having a width less than said reed so as to form a pair of shoulders at said connection, said armature cooperating with said pole piece to activate said reed upon excitation of said coil, vibrator contact arms separate from said vibratory reed included by second support means held on said reed and adapted to move therewith, one of said arm being a driver contact arm lying flat against said reed and having its contact placed above said shoulder of said reed adjacent said neck of said armature, said contact on said arm adapted to meet a fixed contact held on an arm connected to said frame, each of said other arms having a frictional backing continuously slideably engaged therewith, and relatively fixed side contact arms held in said first reed supporting means and adapted to make contact with said reed contacts upon the operation of said reed.

9. A vibrator comprising in combination, a vibratory reed having a free end, means for supporting another end of said reed, a driver coil, a frame having an end connected to said reed end supporting means for holding said coil, said frame further bent to have a hook-like configuration including a dependent portion, said dependent portion penetrating said coil substantially at the center thereof and having its end constructed as a magnetic pole piece, said pole piece and dependent portion both having end widths less than the width of the frame from which said latter depends, said support means for said reed and said frame being positioned substantially below said pole piece, a U-shaped armature connected to said reed and cooperating with said pole piece to activate said reed upon excitation of said coil, vibrator contact bearing arms separate from said vibrator reed included by second support means held on said reed and adapted to move therewith, each of said vibrator contact bearing arms having a truncated frictional backing continuously slideably engaged therewith only beneath said contacts, and relatively fixed side contact arms held in said first reed supporting means and adapted to make contact with said reed contacts upon the operation of said reed.

CLARENCE HUETTEN.

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